How to add a call-to-action button with Claude

Add a call-to-action button to input.mp4: a pink (255, 45, 110) pill-shaped button 64% of the frame width and 9% of its height, centered across and 82% of the way down, with "SHOP NOW" in white bold text and a white chevron after it, on a soft dark shadow. It pops in at 3.5 seconds, growing from nothing to full size over 0.3 seconds with a slight overshoot, then pulses until the end: it smoothly swells to 110% and back every 0.8 seconds, and at the top of each pulse a 4-pixel white outline of the button spreads outward and fades over 0.8 seconds. Nothing shows before 3.5 seconds. Use Python with Pillow to draw it and ffmpeg to put it on the video (don't rely on ffmpeg's drawtext filter), keep the audio, and save it as output.mp4.

#!/usr/bin/env python3
"""Call-to-action button: a pink "SHOP NOW" button pops up near the end and keeps pulsing, as if waiting to be tapped.

Usage: python3 call-to-action-button.py input.mp4 output.mp4
Needs ffmpeg and Pillow (pip install pillow).
"""
import json
import math
import subprocess
import sys
from pathlib import Path

from PIL import Image, ImageDraw, ImageFont

LABEL = "SHOP NOW"       # button text
START = 3.5              # second the button pops in
POP = 0.3                # seconds the pop takes
PERIOD = 0.8             # seconds per pulse once it has landed
PULSE = 0.10             # how much bigger the button gets at the top of each pulse
WIDTH, HEIGHT = 0.64, 0.09  # button size as a share of the frame width and height
Y = 0.82                 # button center, 0-1 down the frame (centered across)
COLOR = (255, 45, 110)   # button color
FONTS = ["/System/Library/Fonts/Supplemental/Arial Bold.ttf",     # macOS
         "/usr/share/fonts/truetype/dejavu/DejaVuSans-Bold.ttf",  # Linux
         "C:/Windows/Fonts/arialbd.ttf"]                          # Windows
FONT_FILE = next((f for f in FONTS if Path(f).exists()), None) or sys.exit("No bold font found: add one to FONTS")


def button():
    """The button at full size: a pill with the label and a chevron, on a soft shadow."""
    bw, bh, pad = round(w * WIDTH), round(h * HEIGHT), round(h * HEIGHT * 0.3)
    img = Image.new("RGBA", (bw + 2 * pad, bh + 2 * pad))
    draw = ImageDraw.Draw(img)
    draw.rounded_rectangle([pad, pad + bh * 0.08, pad + bw, pad + bh * 1.08], bh / 2, fill=(0, 0, 0, 90))
    draw.rounded_rectangle([pad, pad, pad + bw, pad + bh], bh / 2, fill=COLOR)
    font = ImageFont.truetype(FONT_FILE, round(bh * 0.38))
    text_w = draw.textlength(LABEL, font=font)
    arrow = bh * 0.16
    left = pad + (bw - text_w - arrow * 2.2) / 2
    draw.text((left, pad + bh / 2), LABEL, font=font, anchor="lm", fill="white")
    ax, ay = left + text_w + arrow * 1.4, pad + bh / 2
    draw.line([(ax, ay - arrow), (ax + arrow * 0.8, ay), (ax, ay + arrow)], fill="white", width=max(3, bh // 14), joint="curve")
    return img


def scale_at(t):
    """0 before START, a springy pop to 1, then a steady pulse between 1 and 1 + PULSE."""
    if t < START:
        return 0
    if t < START + POP:
        return ease_out_back((t - START) / POP)
    return 1 + PULSE * (0.5 - 0.5 * math.cos(2 * math.pi * (t - START - POP) / PERIOD))


def ring_at(t):
    """A white ring that spreads out from the button and fades at the top of each pulse: (growth, opacity)."""
    since = t - START - POP - PERIOD / 2
    if since < 0:
        return None
    p = (since % PERIOD) / PERIOD
    return 1 + PULSE + 0.25 * p, round(200 * (1 - p))


def overlay(t):
    img = Image.new("RGBA", (w, h))
    s = scale_at(t)
    if s < 0.02:
        return img
    cx, cy = w / 2, h * Y
    ring = ring_at(t)
    if ring:
        grow, alpha = ring
        rw, rh = w * WIDTH * grow / 2, h * HEIGHT * (1 + (grow - 1) * 2.5) / 2
        ImageDraw.Draw(img).rounded_rectangle([cx - rw, cy - rh, cx + rw, cy + rh], rh, outline=(255, 255, 255, alpha), width=4)
    b = full.resize((max(1, round(full.width * s)), max(1, round(full.height * s))), Image.LANCZOS)
    img.alpha_composite(b, (round(cx - b.width / 2), round(cy - b.height / 2)))
    return img


def ease_out_back(p):
    """0 -> 1 with a small overshoot past 1 before settling, which reads as a 'pop'."""
    p = min(max(p, 0), 1)
    return 1 + 2.70158 * (p - 1) ** 3 + 1.70158 * (p - 1) ** 2


def probe(path):
    info = json.loads(subprocess.check_output(["ffprobe", "-v", "error", "-select_streams", "v:0", "-show_entries",
                                               "stream=width,height,r_frame_rate:format=duration", "-of", "json", path]))
    s = info["streams"][0]
    num, den = s["r_frame_rate"].split("/")
    return s["width"], s["height"], s["r_frame_rate"], float(num) / float(den), float(info["format"]["duration"])


def render(src, out):
    """Draw overlay(t) on every frame of src and save to out, keeping the audio."""
    ff = subprocess.Popen(["ffmpeg", "-y", "-v", "error", "-i", src,
                           "-f", "rawvideo", "-pix_fmt", "rgba", "-s", f"{w}x{h}", "-r", rate, "-i", "-",
                           "-filter_complex", "[0:v][1:v]overlay=shortest=1,format=yuv420p[v]",
                           "-map", "[v]", "-map", "0:a?", "-c:v", "libx264", "-crf", "18", "-c:a", "copy", out],
                          stdin=subprocess.PIPE)
    for i in range(math.ceil(duration * fps)):
        ff.stdin.write(overlay(i / fps).tobytes())
    ff.stdin.close()
    if ff.wait():
        sys.exit("ffmpeg failed")


src, out = sys.argv[1:3]
w, h, rate, fps, duration = probe(src)
full = button()
render(src, out)